The invention relates to a welded lap or web joint for galvanized sheets of the generic type disclosed, for example, by JP-56-62-688(A).
In JP-56-62 688 (A), in order to avoid gas pockets of the zinc coating in the weld pool, which zinc coating vaporizes during welding, inserts which ensure the distancing of the sheets are adhesively bonded between the sheets in the overlap region on either side of the laser weld. These protrusion-like inserts run parallel to the longitudinal direction of the laser weld and are at a mutual transverse distance apart which is greater than the width of the weld. Consequently, during welding there are two large-area alignment channels, directed transversely to the longitudinal direction of the laser weld, for the vaporizing zinc. Although this method proves to be reliable with regard to its function, it is too time-consuming and costly for production, since an additional material has to be arranged between the sheets. Furthermore, in the specification defining the generic type, a further example is cited in which, in the overlap region, a longitudinal bead following the course of the weld and having a trapezoidal cross-section is pressed into one of the sheets, which longitudinal bead, with the mating sheet, forms a longitudinal channel, following the course of the weld, for the zinc vapor. In such an arrangement, however, considerable flow resistance which impairs the drainage action may possibly result.
The object of the present invention is therefore to provide a welded lap or web joint such that galvanized sheets can be welded more cost-effectively.
This and other and other objects are achieved according to the invention by protrusions or beads pressed into the sheet. When the sheets are clamped against one another, these beads ensure the spacing of the sheet layers in the overlap region, and thus the short alignment channels running in two directions transversely to the laser weld.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.